The NCI-atlas of dose distributions for regular 125I brain implants

In connection with the development of an optimization method for 125I brain implants in irregularly shaped target volumes, a systematic study was conducted toward optimizing seed configurations for regular target volumes. The intention was to find basic rules for the positioning of strings of seeds in the cylindrical implant pattern of the stereotactic neurosurgical procedure in use, and in accordance with the following criteria: (i) steep dose fall-off outside the target volume; (ii) coverage of the target volume by making the prescribed dose surface coincident with the target volume surface within 1 mm; (iii) uniformity of the dose distribution in the target volume as far as achievable with a seed implant. As a result of this study, an atlas of optimized regular 125I brain implant configurations was compiled. Regular implants were understood as being cylindrical or spherical. Diameters and heights from 2 to 5 cm were covered.